Method for producing base for metal masks, method for producing metal mask for vapor deposition, base for metal masks, and metal mask for vapor deposition

ABSTRACT

A rolled metal sheet includes an obverse surface and a reverse surface that is a surface located opposite to the obverse surface. At least either one of the obverse surface and the reverse surface is a processing object. A method for manufacturing a metal mask substrate includes reducing a thickness of the rolled metal sheet to 10 μm or less by etching the processing object by 3 μm or more by use of an acidic etching liquid, and roughening the processing object so that the processing object becomes a resist formation surface that has a surface roughness Rz of 0.2 μm or more, thereby obtaining a metal mask sheet.

BACKGROUND

The present disclosure relates to a method for manufacturing a metalmask substrate, a method for manufacturing a vapor deposition metal maskby use of a metal mask substrate, a metal mask substrate, and a vapordeposition metal mask.

Background Art

An organic EL display is known as one of the display devicesmanufactured according to a vapor deposition method. An organic layerincluded in the organic EL display is a deposit of organic moleculessublimed in a vapor deposition step. An opening of a metal mask used inthe vapor deposition step is a passageway through which the sublimedorganic molecules pass, and has a shape corresponding to the shape ofpixels in the organic EL display (see Japanese Laid-Open PatentPublication No. 2015-055007, for example).

With the improvement of display quality in a display device or with theadvancement of high definition of a display device, film formation byuse of a metal mask is desired to realize high definition in the organicEL display or in a metal mask that determines a pixel size. In recentyears, an organic EL display has been desired to realize high definitionof 700 ppi or more, and therefore a metal mask capable of forming anorganic layer in such a high-definition organic EL display has beendesired.

The realization of high definition of film formation by use of a metalmask has been desired in the formation of wiring of various devices orbeen desired in vapor deposition by use of a metal mask of a functionallayer or the like of various devices without being limited to themanufacturing of display devices including an organic EL display.

SUMMARY

It is an objective of the present disclosure to provide a method formanufacturing a metal mask substrate, a method for manufacturing a vapordeposition metal mask, a metal mask substrate, and a vapor depositionmetal mask that are capable of realizing high definition of filmformation by use of a vapor deposition metal mask.

To achieve the foregoing objective and in accordance with one aspect ofthe present disclosure, a method for manufacturing a metal masksubstrate is provided. The method includes: preparing a rolled metalsheet, the rolled metal sheet including an obverse surface and a reversesurface that is a surface located opposite to the obverse surface, atleast either one of the obverse surface and the reverse surface being anobject to be processed; and reducing a thickness of the rolled metalsheet to 10 μm or less by etching the object to be processed by 3 μm ormore by use of an acidic etching liquid, and roughening the object to beprocessed so that the processing object becomes a resist formationsurface that has a surface roughness Rz of 0.2 μm or more, therebyobtaining a metal mask sheet.

To achieve the foregoing objective and in accordance with one aspect ofthe present disclosure, a method for manufacturing a vapor depositionmetal mask is provided. The method includes: forming a metal masksubstrate that includes at least one resist formation surface; forming aresist layer on the one resist formation surface; forming a resist maskby subjecting the resist layer to patterning; and etching the metal masksubstrate by use of the resist mask. The metal mask substrate is formedby use of the above described method for manufacturing a metal masksubstrate.

To achieve the foregoing objective and in accordance with one aspect ofthe present disclosure, a metal mask substrate is provided that includesa metal sheet that includes an obverse surface and a reverse surfacelocated opposite to the obverse surface. At least either one of theobverse surface and the reverse surface is a resist formation surface. Athickness of the metal sheet is 10 μm or less. A surface roughness Rz ofthe resist formation surface is 0.2 μm or more.

To achieve the foregoing objective and in accordance with one aspect ofthe present disclosure, a vapor deposition metal mask that includes ametal mask substrate is provided. The metal mask substrate is theabove-described metal mask substrate. The metal sheet included in themetal mask substrate has a plurality of through-holes that pass throughbetween the obverse surface and the reverse surface.

With the aforementioned configuration, the thickness of the metal masksheet is 10 μm or less, and it is thus possible to set the depth of amask opening formed in the metal mask sheet at 10 μm or less. Therefore,it is possible to reduce a part that is hidden by the vapor depositionmetal mask when a film-formation object is viewed from a depositedparticle, i.e., it is possible to restrain a shadow effect. It is thuspossible to obtain a shape conforming with the shape of a mask openingat the film-formation object, and, consequently, it is possible torealize high definition of film formation by use of the vapor depositionmetal mask. Additionally, when a resist layer is formed on the resistformation surface in order to form a mask opening in the metal masksheet, it is first possible to make adhesion between the resist layerand the metal mask substrate higher than before being roughened. Stilladditionally, it is possible to restrain the form accuracy from beingreduced because of, for example, the peeling off of the resist layerfrom the metal mask sheet in the formation of the mask opening. In thisrespect, it is possible to realize high definition of film formation byuse of the vapor deposition metal mask.

In the above-described method for manufacturing a metal mask substrate,the object to be processed may comprise both the obverse surface and thereverse surface.

With the aforementioned configuration, it is possible to form a resistlayer on either resist formation surface, i.e., on either the resistformation surface formed from the obverse surface or the resistformation surface formed from the reverse surface. Therefore, it ispossible to restrain adhesion between the resist layer and the metalmask substrate from becoming difficult to obtain because of mistakingthe surface of an object on which the resist layer is formed.Consequently, it is possible to restrain the yield from being reducedwhen a vapor deposition metal mask is manufactured.

In the above-described method for manufacturing a metal mask substrate,the object to be processed is either the obverse surface or the reversesurface. The method further includes stacking a plastic support layer ona surface located opposite to the object to be processed. The object tobe processed is etched in a state in which the rolled metal sheet andthe support layer are stacked together, thereby obtaining a metal masksubstrate, in which the metal mask sheet and the support layer arestacked together.

In the above-described method for manufacturing a metal mask substrate,the etching includes etching a first object to be processed that iseither one of the obverse surface and the reverse surface and thenetching a second object to be processed that is the remaining one of theobverse surface and the reverse surface. The method further includesetching the first object to be processed and then stacking a plasticsupport layer on the resist formation surface that has been obtained byetching the first object to be processed. The second object to beprocessed is etched in a state in which the rolled metal sheet and thesupport layer are stacked together, thereby obtaining a metal masksubstrate in which the metal mask sheet and the support layer arestacked together.

With the aforementioned configuration, it is possible to reduce thecomplexity of handling of the metal mask sheet that results from thefragility of the metal mask sheet caused by the fact that the thicknessof the metal mask sheet is 10 μm or less when the metal mask sheet isconveyed or when post-processing is applied to the metal mask sheet.

In the above-described method for manufacturing a metal mask substrate,the rolled metal sheet is preferably a rolled invar sheet, and the metalmask sheet is preferably an invar sheet.

With the aforementioned configuration, if the film-formation object is aglass substrate, the linear expansion coefficient of the glass substrateand the linear expansion coefficient of invar are substantially equal toeach other. It is thus possible to apply a metal mask formed from themetal mask substrate to film formation on the glass substrate. That is,it is possible to apply a metal mask of which the form accuracy has beenraised to film formation on the glass substrate.

In the above-described method for manufacturing a vapor deposition metalmask, the metal mask substrate preferably includes a laminate of themetal mask sheet and the plastic support layer. The method furtherincludes chemically removing the support layer from the metal masksubstrate by exposing, to alkaline solution, the metal mask substrate,in which the resist mask has been formed.

With the aforementioned configuration, an external force does not act onthe metal mask sheet, and therefore the metal mask sheet is restrainedfrom being rumpled or distorted in comparison with a case in which thesupport layer is physically peeled off from the metal mask sheet.

In the above-described metal mask substrate, the resist formationsurface may have particle traces that are a plurality of hollows each ofwhich is shaped like an elliptic cone, and major axes of the particletraces may be aligned.

The metal sheet is normally manufactured by rolling, and therefore thereare not a few cases in which particles of, for example, oxides of adeoxidizer that is added during a process for manufacturing the metalsheet are mixed into the metal sheet. The particles that have been mixedinto the obverse surface of the metal sheet are extended in the rolleddirection of a metal material so as to be shaped like elliptic coneshaving the major axes aligned extending in the rolled direction. If suchparticles remain in a part in which a mask opening is formed in theresist formation surface, etching to form the mask opening may behindered by the particles.

In this respect, with the aforementioned configuration, the resistformation surface has a plurality of particle traces shaped likeelliptic cones with aligned major axes, respectively, i.e., theaforementioned particles have already been removed from the resistformation surface. Thus, when a mask opening is formed, it is alsopossible to make the form accuracy or size accuracy of the mask openinghigher.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view showing a perspective structure of a metalmask substrate according to one embodiment of the present disclosure.

FIG. 2 is a process diagram showing a step of preparing a rolled invarsheet in a method for manufacturing a vapor deposition metal mask.

FIG. 3 is a process diagram showing a step of etching a reverse surfaceof a rolled invar sheet in the method for manufacturing a vapordeposition metal mask.

FIG. 4 is a process diagram showing a step of forming a support layer ona resist formation surface of a rolled invar sheet in the method formanufacturing a vapor deposition metal mask.

FIG. 5 is a process diagram showing a step of etching an obverse surfaceof the rolled invar sheet in the method for manufacturing a vapordeposition metal mask.

FIG. 6 is a schematic diagram that schematically shows the distributionof a metal oxide in the rolled invar sheet.

FIG. 7 is a process diagram showing a step of forming a resist layer inthe method for manufacturing a vapor deposition metal mask.

FIG. 8 is a process diagram showing a step of forming a resist mask inthe method for manufacturing a vapor deposition metal mask.

FIG. 9 is a process diagram showing a step of etching an invar sheet inthe method for manufacturing a vapor deposition metal mask.

FIG. 10 is a cross-sectional view showing a sectional shape of athrough-hole formed by etching both the obverse surface and the reversesurface of the invar sheet.

FIG. 11 is a process diagram showing a step of removing the resist maskin the method for manufacturing a vapor deposition metal mask.

FIG. 12 is a process diagram showing a step of chemically removing thesupport layer in the method for manufacturing a vapor deposition metalmask.

FIG. 13 is a cross-sectional view showing a cross-sectional structure ofa vapor deposition metal mask bonded to a frame.

FIG. 14 is a plan view showing a plane structure of the vapor depositionmetal mask bonded to the frame.

FIG. 15 is a SEM image obtained by photographing the obverse surface ofa rolled invar sheet of Test Example 1.

FIG. 16 is a SEM image obtained by photographing a resist formationsurface of an invar sheet of Test Example 2.

FIG. 17 is a SEM image obtained by photographing a resist formationsurface of an invar sheet of Test Example 3.

FIG. 18 is a SEM image obtained by photographing a resist formationsurface of an invar sheet of Test Example 4.

FIG. 19 is a SEM image obtained by photographing a first particle trace.

FIG. 20 is a SEM image obtained by photographing a second particletrace.

FIG. 21 is a cross-sectional view showing a cross-sectional structurebetween a metal mask and a frame in a modification.

FIG. 22 is a cross-sectional view showing a cross-sectional structurebetween a metal mask and a frame in a modification.

FIG. 23 is a plan view showing a plane structure of an invar sheet in amodification.

DESCRIPTION OF EXEMPLARY EMBODIMENTS

Referring to FIGS. 1 to 20, a description will be given of oneembodiment in which a method for manufacturing a metal mask substrate, amethod for manufacturing a vapor deposition metal mask, a metal masksubstrate, and a vapor deposition metal mask are embodied. In thepresent embodiment, a vapor deposition metal mask that is used to forman organic layer of an organic EL device will be described as an exampleof a vapor deposition metal mask. Hereinafter, a configuration of ametal mask substrate, a method for manufacturing a vapor depositionmetal mask including a method for manufacturing a metal mask substrate,and test examples will be described in this order.

Configuration of a Metal Mask Substrate

A configuration of a metal mask substrate will be described withreference to FIG. 1.

As shown in FIG. 1, a metal mask substrate 10 is an example of a metalmask sheet, and includes an invar sheet 11 that is an invar metal masksheet. The invar sheet 11 is composed of an obverse surface 11 a and areverse surface 11 b that is a surface on the side opposite to theobverse surface 11 a. In the invar sheet 11, the obverse surface 11 aand the reverse surface 11 b are surfaces to be processed for resist,respectively, and are surfaces on each of which a resist layer can beformed when the invar sheet 11 is etched.

The thickness T1 of the invar sheet 11 is 10 μm or less, and the surfaceroughness Rz in the obverse surface 11 a and the surface roughness Rz inthe reverse surface 11 b are each 0.2 μm or more.

The thickness of the invar sheet 11 is 10 μm or less, and it is thuspossible to set the depth of a mask opening formed in the invar sheet 11at 10 μm or less. Therefore, it is possible to reduce a part that ishidden by the vapor deposition metal mask when a film-formation objecton which a film is formed is seen from a deposited particle, i.e., it ispossible to restrain a shadow effect. It is thus possible to obtain ashape conforming with the shape of the mask opening in thefilm-formation object, and it is possible to realize high definition offilm formation by use of the vapor deposition metal mask.

Additionally, when a resist layer is formed on the obverse surface 11 ain order to form a mask opening in the invar sheet 11, it is firstpossible to make adhesion between the resist layer and the invar sheet11 higher than before being roughened. Still additionally, it ispossible to restrain form accuracy from being reduced because of, forexample, the peeling off of the resist layer from the invar sheet 11 inthe formation of the mask opening. Thus, in this respect also, it ispossible to realize high definition of film formation by use of thevapor deposition metal mask.

The material of which the invar sheet 11 is made is a nickel-iron alloythat includes nickel of 36 mass % and iron, i.e., is invar, and thethermal expansion coefficient of the invar sheet 11 is about 1.2×10⁻⁶/°C.

The thermal expansion coefficient of the invar sheet 11 and the thermalexpansion coefficient of a glass substrate that is an example of afilm-formation object on which a film is formed are substantially equalto each other. Therefore, it is possible to apply a vapor depositionmetal mask manufactured by use of the metal mask substrate 10 to filmformation on the glass substrate, i.e., it is possible to apply a vapordeposition metal mask of which the form accuracy has been raised to filmformation on the glass substrate.

The surface roughness Rz in the obverse surface of the invar sheet 11 isa value measured by a method conforming to JIS B 0601-2001. The surfaceroughness Rz is a maximum height in a contour curve that has a referencelength.

The metal mask substrate 10 additionally includes a plastic supportlayer 12, and is a laminate consisting of the invar sheet 11 and thesupport layer 12. Among all parts of the invar sheet 11, the reversesurface 11 b adheres closely to the support layer 12. The material thatforms the support layer 12 is at least one of, for example, a polyimideand a negative resist. The support layer 12 may be a polyimide layer ormay be a negative-resist layer. Alternatively, the support layer 12 maybe a laminate consisting of a polyimide layer and a negative-resistlayer.

Among these, the thermal expansion coefficient of a polyimide shows thesame tendency as the thermal expansion coefficient of invar astemperature dependence, and is substantially equal in value to thethermal expansion coefficient of invar. Therefore, if the materialforming the support layer 12 is a polyimide, it is possible to morereliably restrain the metal mask substrate 10 and the invar sheet 11from being warped by a change in temperature in the metal mask substrate10 than in a case in which the support layer 12 is made of plastic otherthan a polyimide.

Method for Manufacturing a Vapor Deposition Metal Mask

Referring to FIGS. 2 to 12, a description will be given of a method formanufacturing a vapor deposition metal mask.

As shown in FIG. 2, the manufacturing method of a vapor deposition metalmask includes a method for manufacturing a metal mask substrate 10. Inthe manufacturing method of the metal mask substrate 10, a rolled invarsheet 21 that is an example of a rolled metal sheet is first prepared.The rolled invar sheet 21 is composed of an obverse surface 21 a and areverse surface 21 b that is a surface on the side opposite to theobverse surface 21 a, and, among all parts of the rolled invar sheet 21,the obverse surface 21 a and the reverse surface 21 b are objects to beprocessed, respectively, in the manufacturing method of the metal masksubstrate 10.

The rolled invar sheet 21 is obtainable by rolling out an invar basematerial and by annealing the base material that has been rolled out.The surface roughness Rz of each of the obverse and reverse surfaces 21a and 21 b of the rolled invar sheet 21 becomes smaller than the surfaceroughness Rz of each of the obverse and reverse surfaces of the basematerial in proportion to a reduction in the level difference of theobverse and reverse surfaces of the base material that is caused byrolling out the rolled invar sheet 21.

The thickness T2 of the rolled invar sheet 21 is, for example, 10 μm ormore and 100 μm or less, and more preferably, 10 μm or more and 50 μm orless.

The reverse surface 21 b is one object to be processed that is etchedearlier in the two objects to be processed, and is an example of a firstobject to be processed. As shown in FIG. 3, the reverse surface 21 b isetched with an acidic etching liquid by 3 μm or more. The differencebetween the reverse surface 21 b of the rolled invar sheet 21 that hasnot yet been etched and the reverse surface of the rolled invar sheet 21that has been etched, i.e., between the reverse surface 21 b of therolled invar sheet 21 that has not yet been etched and a resistformation surface 21 c is an etching thickness T3. The etching thicknessT3 is 3 μm or more.

The thickness of the rolled invar sheet 21 is made smaller by etchingthe reverse surface 21 b than before etching the reverse surface 21 b,and the reverse surface 21 b is roughened so that the resist formationsurface 21 c has a surface roughness Rz of 0.2 μm or more.

The acidic etching liquid is recommended to be an etching liquid that iscapable of etching invar, and is recommended to be solution having acomposition that makes the reverse surface 21 b of the rolled invarsheet 21 rougher than before the reverse surface 21 b is etched. Theacidic etching liquid is solution created by mixing any one ofperchloric acid, hydrochloric acid, sulfuric acid, formic acid, andacetic acid, for example, with ferric perchlorate solution and with amixture of ferric perchlorate solution and ferric chloride solution. Thereverse surface 21 b may be etched according to a dip way in which therolled invar sheet 21 is dipped in an acidic etching liquid, oraccording to a spray way in which an acidic etching liquid is sprayedonto the reverse surface 21 b of the rolled invar sheet 21, or accordingto a spin way in which an acidic etching liquid is dropped to the rolledinvar sheet 21 rotated by a spinner.

The etching thickness T3 is recommended to be at least 3 μm, preferably10 μm or more, and more preferably 15 μm or more.

As shown in FIG. 4, the reverse surface 21 b of the rolled invar sheet21 is etched, and then the plastic support layer 12 is stacked on theresist formation surface 21 c, which has been obtained by etching thereverse surface 21 b. The thickness T4 of the support layer 12 is, forexample, 10 μm or more and 50 μm or less.

Preferably, the thickness of the support layer 12 is 10 μm or more inthe fact that the strength of a laminate consisting of the support layer12 and the rolled invar sheet 21 is raised to such a degree as to reducethe complexity of handling that results from the fragility of thelaminate in a process of manufacturing the metal mask substrate 10 evenif the thickness of the rolled invar sheet 21 is 10 μm or less.

Additionally, preferably, the thickness of the support layer 12 is 50 μmor less in the fact that a period of time required when the supportlayer 12 is removed from the metal mask substrate 10 by means ofalkaline solution is restrained from being excessively lengthened.

The support layer 12 may be stacked on the resist formation surface 21 cby being bonded to the resist formation surface 21 c after being formedinto a sheet shape. Alternatively, the support layer 12 may be stackedon the resist formation surface 21 c by applying an application liquidused to form the support layer 12 onto the resist formation surface 21c.

If the support layer 12 includes the aforementioned negative-resistlayer, after a film of a negative resist is bonded to the resistformation surface 21 c or after a negative resist is applied to theresist formation surface 21 c, ultraviolet rays are radiated to theentire negative resist so as to form the support layer 12.

As shown in FIG. 5, in a state in which the rolled invar sheet 21 andthe support layer 12 are stacked together, the obverse surface 21 a ofthe rolled invar sheet 21, which is an example of a second object to beprocessed that is etched after the first object to be processed isetched, is etched with an acidic etching liquid by 3 μm or more. Thedifference between the obverse surface 21 a of the rolled invar sheet 21that has not yet been etched and the rolled invar sheet 21 that has beenetched, i.e., between the obverse surface 21 a of the rolled invar sheet21 that has not yet been etched and the obverse surface 11 a of theinvar sheet 11 is an etching thickness T5. The etching thickness T5 is 3μm or more.

As thus described, the etching of the rolled invar sheet 21 includes thefact that the reverse surface 21 b of the rolled invar sheet 21 that isan example of the first object to be processed is etched and the factthat, thereafter, the obverse surface 21 a that is an example of thesecond object to be processed is etched.

The thickness T2 of the rolled invar sheet 21 previously described withreference to FIG. 2 is set at 10 μm or less by etching the obversesurface 21 a, and the obverse surface 21 a is roughened so that theobverse surface 21 a has a surface roughness Rz of 0.2 μm or more. Thismakes it possible to obtain the invar sheet 11 that is an example of ametal metal mask sheet and of a metal sheet and that has a surfaceroughness Rz of 0.2 μm or more in each of the obverse and reversesurfaces 11 a and 11 b and to obtain the metal mask substrate 10 inwhich the invar sheet 11 and the support layer 12 are stacked together.

Both the obverse surface 21 a and the reverse surface 21 b of the rolledinvar sheet 21 are etched, and it is thus possible to form a resistlayer on either resist formation surface, i.e., on either the resistformation surface formed from the obverse surface 21 a or the resistformation surface 21 c formed from the reverse surface 21 b. Therefore,it is possible to restrain adhesion between the resist layer and themetal mask substrate 10 from becoming difficult to obtain because ofmistaking the surface of an object on which a resist layer is formed,and, consequently, it is possible to restrain a yield from being reducedwhen a metal mask 51 for vapor deposition is manufactured.

The metal mask substrate 10 is a laminate consisting of the invar sheet11 and the support layer 12. Therefore, it is possible to reduce thecomplexity of handling of the invar sheet 11 that results from thefragility of the invar sheet 11 caused by the fact that the thickness ofthe invar sheet 11 is 10 μm or less when the invar sheet 11 is conveyedor when post-processing is applied to the invar sheet 11.

The acidic etching liquid is recommended to be any one of the acidicetching liquids used to etch the reverse surface 21 b, and, preferably,is the same as the acidic etching liquid used to etch the reversesurface 21 b. Additionally, preferably, the obverse surface 21 a isetched according to the same way as the reverse surface 21 b is etchedalthough the obverse surface 21 a may be etched according to any one ofthe dip way, the spray way, and the spin way.

The etching thickness T5 is recommended to be at least 3 μm, and ispreferably 10 μm or more, and is more preferably 15 μm or more. Theetching thickness T5 and the aforementioned etching thickness T3 may beequal to each other, or may be different from each other.

Normally, when a base material of the rolled invar sheet 21 is formed,for example, granular aluminum, magnesium, or the like, which serves asa deoxidizer, is mixed with materials forming the base material in orderto remove oxygen that has infiltrated into the materials forming thebase material. Aluminum and magnesium are oxidized, and are included inthe materials forming the base material in a state of metal oxides, suchas an aluminum oxide and a magnesium oxide. When a base material isformed, some of the metal oxides are left inside the base materialalthough most of the metal oxides are removed from the base material.

As shown in FIG. 6, among all parts of the rolled invar sheet 21, a partincluding the center in the thickness direction of the rolled invarsheet 21 is a central part C, and a part including the obverse surface21 a is a first surface layer part S1, and a part including the reversesurface 21 b is a second surface layer part S2. The metal oxide isdistributed at the first surface layer part S1 and at the second surfacelayer part S2 more than at the central part C.

The metal oxide is one cause that leads to the fact that a resist ispeeled off from the invar sheet 11 or the fact that the invar sheet 11is etched excessively when a vapor deposition metal mask is formed byetching the invar sheet 11.

As described above, in the manufacturing method of the metal masksubstrate 10, the obverse surface 21 a and the reverse surface 21 b ofthe rolled invar sheet 21 are etched, and therefore at least a part ofthe first surface layer part S1 and at least one part of the secondsurface layer part S2 each of which includes more metal oxides areremoved. Therefore, the resist is restrained from being peeled offbecause of the metal oxides, or the invar sheet 11 is restrained frombeing excessively etched because of the metal oxides, and the accuracyof etching with respect to the metal mask substrate 10 is restrainedfrom becoming smaller than in a case in which the obverse surface 21 aand the reverse surface 21 b of the rolled invar sheet 21 are notetched.

As shown in FIG. 7, a resist layer 22 is formed on the obverse surface11 a of the invar sheet 11. The resist layer 22 may be formed on theobverse surface 11 a by being formed in a sheet shape and then beingbonded to the obverse surface 11 a. Alternatively, the resist layer 22may be formed on the obverse surface 11 a by applying an applicationliquid that is used to form the resist layer 22 onto the obverse surface11 a.

The material forming the resist layer 22 may be a negative resist, ormay be a positive resist. If the material forming the support layer 12is a negative resist, it is preferable to form the resist layer 22 withthe same material as the support layer 12.

As shown in FIG. 8, a resist mask 23 is formed by patterning the resistlayer 22. The resist mask 23 has a plurality of through-holes 23 a toetch the invar sheet 11.

If the material forming the resist layer 22 is a negative resist,ultraviolet rays are radiated onto parts other than a part correspondingto each through-hole 23 a of the resist mask 23 among all parts of theresist layer 22, and the resist layer 22 is exposed. Thereafter, theresist mask 23 having the through-holes 23 a is obtained by developingthe resist layer 22 with a developer.

If the material forming the resist layer 22 is a positive resist,ultraviolet rays are radiated onto a part corresponding to eachthrough-hole 23 a of the resist mask 23 among all parts of the resistlayer 22, and the resist layer 22 is exposed. Thereafter, the resistmask 23 having the through-holes 23 a is obtained by developing theresist layer 22 with the developer.

As shown in FIG. 9, the invar sheet 11 is etched by use of the resistmask 23. For example, ferric chloride solution is used to etch the invarsheet 11. By this ferric chloride solution, a plurality of through-holes11 c passing through the part between the obverse surface 11 a and thereverse surface 11 b are formed in the invar sheet 11, i.e., a maskopening is formed in the invar sheet 11. The inner peripheral surface ofeach through-hole 11 c has the shape of a substantially inferior arc ina cross section along the thickness direction of the invar sheet 11, andthe opening area in the obverse surface 11 a is larger than the openingarea in the reverse surface 11 b in each through-hole 11 c.

The thickness of the invar sheet 11 is 10 μm or less. Thus, as a resultof merely etching the invar sheet 11 from the obverse surface 11 a, itis possible to form a through-hole 11 c that extends between the obversesurface 11 a and the reverse surface 11 b without excessively enlargingthe mask opening of the invar sheet 11, i.e., without excessivelyenlarging the through-hole 11 c.

As shown in FIG. 10, the thickness T6 of an invar sheet 31 is greaterthan the thickness T1 of the invar sheet 11, i.e., the thickness T6 ofthe invar sheet 31 is greater than 10 μm. In this case, in order to forma through-hole that extends between an obverse surface 31 a and areverse surface 31 b while setting the area of an opening in the obversesurface 31 a of the invar sheet 31 so as to become substantially equalto the area of an opening in the obverse surface 11 a of the invar sheet11, it is necessary to etch the invar sheet 31 from the obverse surface31 a and from the reverse surface 31 b.

As a result, a through-hole 31 e is formed that is composed of a firsthole 31 c opened in the obverse surface 31 a and a second hole 31 dopened in the reverse surface 31 b. In a direction perpendicular to thethickness of the invar sheet 31, the opening area of a connectionportion between the first hole 31 c and the second hole 31 d is smallerthan the opening area of the second hole 31 d of the reverse surface 31b.

When the invar sheet 31 that has the thus configured through-hole 31 eis used as a vapor deposition metal mask, the invar sheet 31 is disposedbetween a vapor deposition source and a film-formation object in a statein which the reverse surface 31 b of the invar sheet 31 faces thefilm-formation object. The connection portion forms a part that ishidden by the vapor deposition metal mask among all parts of the invarsheet 31 when the film-formation object is viewed from a depositedparticle. Correspondingly, a shape conforming with the shape of the maskopening in the second hole 31 d is not obtained easily in thefilm-formation object. Therefore, it is preferable to make the depth ofthe second hole 31 d small, i.e., to make the distance between thereverse surface 31 b and the connection portion small.

In contrast, according to the through-hole 11 c of the invar sheet 11,it is possible to, when the film-formation object is viewed from adeposited particle, make a part that is hidden by the vapor depositionmetal mask smaller than the aforementioned invar sheet 31correspondingly to the fact that the connection portion is not present.As a result, it is possible to obtain a shape further conforming withthe shape of the mask opening in the film-formation object.

As shown in FIG. 11, the resist mask 23, which is the resist mask 23previously described with reference to FIG. 9 and which is located onthe metal mask substrate 10, is removed. When the resist mask 23 isremoved from the laminate consisting of the metal mask substrate 10 andthe resist mask 23, a protective layer that protects the support layer12 may be formed on a surface on the side opposite to a surfacecontiguous to the invar sheet 11 among all parts of the support layer12. The protective layer restrains the support layer 12 from beingdissolved by the solution that removes the resist mask 23.

As shown in FIG. 12, the resist mask 23 is removed, and then the metalmask substrate 10 is exposed to alkaline solution, and, as a result, thesupport layer 12 is chemically removed from the metal mask substrate 10.As a result, a metal mask sheet 41 for vapor deposition is obtained. Themetal mask sheet 41 for vapor deposition has an obverse surface 41 acorresponding to the obverse surface 11 a of the invar sheet 11, areverse surface 41 b corresponding to the reverse surface 11 b of theinvar sheet 11, and a through-hole 41 c corresponding to thethrough-hole 11 c of the invar sheet 11.

At this time, the support layer 12 is chemically removed from the metalmask substrate 10, and therefore an external force does not act on theinvar sheet 11, and the invar sheet 11 is restrained from being rumpledor distorted in comparison with a case in which the support layer 12 isphysically peeled off from the invar sheet 11.

The alkaline solution is merely required to be solution capable ofpeeling off the support layer 12 from the invar sheet 11 by dissolvingthe support layer 12, and is, for example, sodium hydroxide aqueoussolution. When the metal mask substrate 10 is exposed to alkalinesolution, the metal mask substrate 10 may be immersed in the alkalinesolution, or the alkaline solution may be sprayed onto the support layer12 of the metal mask substrate 10, or the alkaline solution may bedropped to the support layer 12 of the metal mask substrate 10 beingrotated by a spinner.

As shown in FIG. 13, a metal mask 51 for vapor deposition that has apredetermined length is cut out from the metal mask sheet 41 for vapordeposition. The metal mask 51 for vapor deposition has an obversesurface 51 a corresponding to the obverse surface 41 a of the metal masksheet 41 for vapor deposition, a reverse surface 51 b corresponding tothe reverse surface 41 b of the metal mask sheet 41 for vapordeposition, and a through-hole 51 c corresponding to the through-hole 41c of the metal mask sheet 41 for vapor deposition.

Thereafter, when the vapor deposition of an organic layer is performed,the metal mask 51 for vapor deposition is bonded to the frame. In otherwords, the metal mask 51 for vapor deposition is used for the vapordeposition of the organic layer in a state of being bonded to a metalframe 52 by means of an adhesive layer 53. In the metal mask 51 forvapor deposition, a part of the reverse surface 51 b of the metal mask51 for vapor deposition faces a part of the frame 52, and the adhesivelayer 53 is located between the metal mask 51 for vapor deposition andthe frame 52. The metal mask 51 for vapor deposition may be bonded tothe frame 52 by means of the adhesive layer 53 in a state in which apart of the obverse surface 51 a of the metal mask 51 for vapordeposition faces a part of the frame 52 and in a state in which theadhesive layer 53 is located between the obverse surface 51 a of themetal mask 51 for vapor deposition and the frame 52.

As shown in FIG. 14, in a plan view that faces the obverse surface 51 aof the metal mask 51 for vapor deposition, the metal mask 51 for vapordeposition has a rectangular shape, and the frame 52 has a rectangularframe shape. In the plan view that faces the obverse surface 51 a, eachthrough-hole 51 c has a rectangular shape. In other words, an opening inthe obverse surface 51 a among the through-holes 51 c has a rectangularshape. Likewise, an opening in the reverse surface 51 b among thethrough-holes 51 c has a rectangular shape. The through-holes 51 c areevenly spaced out in one direction, and are evenly spaced out in anotherdirection perpendicular to the one direction. The metal mask 51 forvapor deposition is disposed between a vapor deposition source and afilm-formation object in a state in which the reverse surface 51 b ofthe metal mask 51 for vapor deposition faces the film-formation object.

In FIG. 14, the left-right direction in drawing is a direction in whichpixels are arranged side by side in the film-formation object.Preferably, the distance between mutually adjoining through-holes 51 cin the left-right direction is twice or more as wide as the width of thethrough-hole 51 c in the left-right direction although the distancebetween the mutually adjoining through-holes 51 c in the left-rightdirection is smaller than the width of the through-hole 51 c in theleft-right direction in FIG. 14.

TEST EXAMPLES

Test examples will be described with reference to FIGS. 15 to 20.

Test Example 1

A rolled invar sheet that had a thickness of 30 μm was prepared, and wasset as a rolled invar sheet of Test Example 1.

Test Example 2

A rolled invar sheet that had a thickness of 30 μm was prepared, and theobverse surface of the rolled invar sheet was etched by 3 μm by sprayingan acidic etching liquid onto the obverse surface of the rolled invarsheet, and an invar sheet of Test Example 2 that had a resist formationsurface was obtained. Solution in which a perchloric acid is mixed witha mixture consisting of ferric perchlorate solution and ferric chloridesolution was used as the acidic etching liquid.

Test Example 3

A rolled invar sheet that had a thickness of 30 μm was prepared, and theobverse surface of the rolled invar sheet was etched by 4.5 μm under thesame condition as in Test Example 2, and an invar sheet of Test Example3 that had a resist formation surface was obtained.

Test Example 4

A rolled invar sheet that had a thickness of 30 μm was prepared, and theobverse surface of the rolled invar sheet was etched by 10 μm under thesame condition as in Test Example 2, and an invar sheet of Test Example4 that had a resist formation surface was obtained.

Photographing of Obverse Surface by Scanning Electron Microscope

The obverse surface of Test Example 1 and the resist formation surfaceof each test example of from Test Example 2 to Test Example 4 werephotographed by a scanning electron microscope, and SEM images weregenerated. The magnification of the scanning electron microscope(JSM-7001F made by JEOL Ltd.) was set at 10000 times, and theacceleration voltage was set at 10.0 kV, and the working distance wasset at 9.7 mm.

As shown in FIG. 15, it was ascertained that the flatness of the obversesurface in the rolled invar sheet of Test Example 1 was the highest, anda rolled trace that was a streak extending in the up-down direction inthe drawing was observed in the obverse surface in the rolled invarsheet of Test Example 1. As shown in FIGS. 16 and 17, it was ascertainedthat a level difference is formed in the resist formation surface in theinvar sheet of Test Example 2 and in the resist formation surface in theinvar sheet of Test Example 3. As shown in FIG. 18, it was ascertainedthat a larger level difference was formed in the resist formationsurface in the invar sheet of Test Example 4 than in the resistformation surface in the invar sheet of Test Example 2 and in the resistformation surface in the invar sheet of Test Example 3. Additionally, itwas ascertained that the rolled trace had substantially disappearedbecause of etching in the resist formation surface in each invar sheetof from FIGS. 16 to 18.

Measurement of Surface Roughness by Atomic Force Microscope

A test piece that included the obverse surface in the rolled invar sheetof Test Example 1 as an obverse surface was created, and a test piecethat included the resist formation surface of the invar sheet in eachtest example of from Test Example 2 to Test Example 4 as an obversesurface was created. Thereafter, the surface roughness in a scan regionthat was a region having a square shape in which the length of a side is5 μm was measured in the obverse surface of each test piece.

The surface roughness in the obverse surface of each test example wasmeasured according to a method conforming to JIS B 0601-2001 by use ofan atomic force microscope (AFM5400L made by Hitachi High-Tech ScienceCorporation). Measurement results of the surface roughness were as shownin Table 1 below. Additionally, based on the measurement results, thesurface area ratio in each test piece was calculated as the ratio of asurface area in a scan region with respect to an area of the scanregion. In other words, the surface area ratio was a value obtained bydividing the surface area in the scan region by the area of the scanregion.

Among parameters of the surface roughness shown in Table 1, Rzdesignates a maximum height that is the sum of the height of the highestcrest and the depth of the deepest trough in a contour curve that has areference length, and Ra designates the arithmetic mean roughness of acontour curve that has a reference length. Rp designates the height ofthe highest crest in a contour curve that has a reference length, and Rvdesignates the depth of the deepest trough in a contour curve that has areference length. In the following description, each unit of Rz, Ra, Rp,and Rv is μm.

TABLE 1 Etching Surface thickness area (μm) Rz Ra Rp Rv ratio Test 00.17 0.02 0.08 0.09 1.02 Example 1 Test 3 0.24 0.02 0.12 0.12 1.23Example 2 Test 4.5 0.28 0.03 0.15 0.13 1.13 Example 3 Test 10 0.30 0.030.17 0.13 1.22 Example 4

As shown in Table 1, in the obverse surface in the rolled invar sheet ofTest Example 1, it was ascertained that the surface roughness Rz was0.17, the surface roughness Ra was 0.02, the surface roughness Rp was0.08, and the surface roughness Rv was 0.09. Additionally, in theobverse surface in the rolled invar sheet of Test Example 1, it wasascertained that the surface area ratio was 1.02.

In the resist formation surface in the invar sheet of Test Example 2, itwas ascertained that the surface roughness Rz was 0.24, the surfaceroughness Ra was 0.02, the surface roughness Rp was 0.12, and thesurface roughness Rv was 0.12. Additionally, in the resist formationsurface in the invar sheet of Test Example 2, it was ascertained thatthe surface area ratio was 1.23.

In the resist formation surface in the invar sheet of Test Example 3, itwas ascertained that the surface roughness Rz was 0.28, the surfaceroughness Ra was 0.03, the surface roughness Rp was 0.15, and thesurface roughness Rv was 0.13. Additionally, in the resist formationsurface in the invar sheet of Test Example 3, it was ascertained thatthe surface area ratio was 1.13.

In the resist formation surface in the invar sheet of Test Example 4, itwas ascertained that the surface roughness Rz was 0.30, the surfaceroughness Ra was 0.03, the surface roughness Rp was 0.17, and thesurface roughness Rv was 0.13. Additionally, in the resist formationsurface in the invar sheet of Test Example 4, it was ascertained thatsurface area ratio was 1.22.

As thus described, in the invar sheet obtained by etching the obversesurface of the rolled invar sheet by 3 μm or more, it was ascertainedthat the surface roughness Rz in the resist formation surface was 0.2 μmor more. Additionally, from the fact that surface roughness Rz in theresist formation surface became larger in proportion to an increase inetching thickness, it was ascertained that the etching thickness in theobverse surface of the rolled invar sheet was preferably 4.5 μm, andmore preferably 10 μm.

A rolled invar sheet that had a thickness of 30 μm was prepared, and aninvar sheet that had a thickness of 10 μm was obtained by etching eachof the obverse and reverse surfaces of the rolled invar sheet by 10 μmunder the aforementioned conditions. At this time, a polyimide sheetthat had a thickness of 20 μm and that served as a support layer wasbonded to the resist formation surface obtained from the reverse surfaceof the rolled invar sheet.

It has been ascertained by the present inventors that it is possible to,with the thus configured invar sheet, form a through-hole that extendsbetween the obverse surface and the reverse surface of the invar sheetmerely by etching the invar sheet from the obverse surface of the invarsheet. Additionally, it has been ascertained by the present inventorsthat, in the thus configured through-hole, the opening area in theobverse surface of the invar sheet and the opening area in the reversesurface of the invar sheet each have a desired extent.

Additionally, a dry film resist was bonded to the obverse surface of therolled invar sheet of Test Example 1, and was subjected to patterning,and then the rolled invar sheet of Test Example 1 was etched so as toform a plurality of concave portions on the obverse surface.

Thereafter, a dry film resist was bonded to the resist formation surfaceof each invar sheet of Test Examples 2 to 4, and was subjected topatterning, and then each invar sheet of Test Examples 2 to 4 was etchedso as to form a plurality of concave portions on the resist formationsurface. In Test Examples 2 to 4, the same method as in Test Example 1was employed as the patterning method of the dry film resist, and theetching conditions of the invar sheet were set to be the same as in TestExample 1.

In each of Test Examples 2 to 4, it was ascertained that variations inthe size of the opening in the resist formation surface were smallerthan variations in the size of the opening in Test Example 1. In otherwords, it was ascertained that, if the surface roughness Rz was 0.2 μmor more as in each of Test Examples 2 to 4, adhesion between the resistlayer and the invar sheet was heightened, and, as a result, the formaccuracy in the mask opening was restrained from being lowered.

Test Example 5

A rolled invar sheet that had a thickness of 30 μm was prepared, and wasset as a rolled invar sheet of Test Example 5.

Test Example 6

A rolled invar sheet that had a thickness of 30 μm was prepared, and theobverse surface of the rolled invar sheet was etched by 3 μm under thesame conditions as in Test Example 2, and an invar sheet of Test Example6 that had a resist formation surface was obtained.

Test Example 7

A rolled invar sheet that had a thickness of 30 μm was prepared, and theobverse surface of the rolled invar sheet was etched by 10 μm under thesame conditions as in Test Example 2, and an invar sheet of Test Example7 that had a resist formation surface was obtained.

Test Example 8

A rolled invar sheet that had a thickness of 30 μm was prepared, and theobverse surface of the rolled invar sheet was etched by 15 μm under thesame conditions as in Test Example 2, and an invar sheet of Test Example8 that had a resist formation surface was obtained.

Test Example 9

A rolled invar sheet that had a thickness of 30 μm was prepared, and theobverse surface of the rolled invar sheet was etched by 16 μm under thesame conditions as in Test Example 2, and an invar sheet of Test Example9 that had a resist formation surface was obtained.

Counting of Particle Traces

Three test pieces were created each of which included a part of theobverse surface in the rolled invar sheet of Test Example 5 as itsobverse surface and each of which had a square shape having a sidelength of 2 mm. Furthermore, three test pieces were created each ofwhich included a part of the resist formation surface in each invarsheet of Test Examples 6 to 9 as its obverse surface and each of whichhad a square shape having a side length of 2 mm.

The obverse surface of each test piece was observed by use of thescanning electron microscope (same as above), and the number of particletraces of each test piece was counted. The particle trace is a tracethat appears from the fact that a particle of a metal oxide has beeneliminated from a rolled invar sheet or from an invar sheet. In eachtest piece, at least either one of a first particle trace and a secondparticle trace was observed. Results obtained by counting the number ofparticle traces were as shown in Table 2 below.

As shown in FIG. 19, the first particle trace defined a substantiallycircular region in a plan view facing the obverse surface of a testpiece, and was a hollow that had a hemispherical shape. It wasascertained that the diameter of the first particle trace was 3 μm ormore and 5 μm or less.

In contrast, as shown in FIG. 20, the second particle trace defined asubstantially elliptical region in a plan view facing the obversesurface of a test piece, and was a hollow that was shaped as an ellipticcone. It was ascertained that the major axis of the second particletrace was 3 μm or more and 5 μm or less.

When the first particle trace and the second particle trace werephotographed, the magnification was set at 5000 times, the accelerationvoltage was set at 10.0 kV, and the working distance was set at 9.7 mmin the scanning electron microscope.

TABLE 2 First Second Total particle particle (number Etching trace traceof traces) thick- (number (number First Second ness Test of of particleparticle (μm) piece No. traces) traces) trace trace Test 0 Test piece 11 0 1 0 Example Test piece 2 0 0 5 Test piece 3 0 0 Test 3 Test piece 14 1 21 3 Example Test piece 2 9 0 6 Test piece 3 8 2 Test 10 Test piece1 5 1 16 4 Example Test piece 2 6 1 7 Test piece 3 5 2 Test 15 Testpiece 1 5 0 13 1 Example Test piece 2 2 0 8 Test piece 3 6 1 Test 16Test piece 1 4 0 14 0 Example Test piece 2 5 0 9 Test piece 3 5 0

As shown in Table 2, in Test Example 5, it was ascertained that testpiece 1 had a single first particle trace, and it was ascertained thatboth test piece 2 and test piece 3 had no particle traces. In otherwords, in Test Example 5, it was ascertained that the total of firstparticle traces was one, and the total of second particle traces waszero.

In Test Example 6, it was ascertained that test piece 1 had four firstparticle traces and one second particle trace, and test piece 2 had ninefirst particle traces, and test piece 3 had eight first particle tracesand two second particle traces. In other words, in Test Example 6, itwas ascertained that the total of first particle traces was twenty-one,and the total of second particle traces was three.

In Test Example 7, it was ascertained that test piece 1 had five firstparticle traces and one second particle trace, and test piece 2 had sixfirst particle traces and one second particle trace, and test piece 3had five first particle traces and two second particle traces. In otherwords, in Test Example 7, it was ascertained that the total of firstparticle traces was sixteen, and the total of second particle traces wasfour.

In Test Example 8, it was ascertained that test piece 1 had five firstparticle traces, and test piece 2 had two first particle traces, andtest piece 3 had six first particle traces and one second particletrace. In other words, in Test Example 8, it was ascertained that thetotal of first particle traces was thirteen, and the total of secondparticle traces was one.

In Test Example 9, it was ascertained that test piece 1 has four firstparticle traces, and test piece 2 had five first particle traces, andtest piece 3 had five first particle traces, while all of test piece 1to test piece 3 had no second particle traces. In other words, in TestExample 9, it was ascertained that the total of first particle traceswas fourteen.

In Test Example 6 and Test Example 7 each of which had a plurality ofsecond particle traces, it was ascertained that major axes in secondparticle traces were uniform, and the major axis direction was parallelto the rolled direction of a rolled invar sheet to form an invar sheet.

As thus described, it was ascertained that it was possible to excludesecond particle traces from the resist formation surface of the invarsheet if the obverse surface of the rolled invar sheet was etched by 16μm or more. Additionally, it was ascertained that it was possible toreduce the number of first particle traces by etching the obversesurface of the rolled invar sheet by 10 μm or more, and it wasascertained that it was possible to further reduce the number of firstparticle traces by etching the obverse surface of the rolled invar sheetby 15 μm or more.

From these results, it can be said that it is possible to reduceparticles of a metal oxide in the rolled invar sheet by etching theobverse surface of the rolled invar sheet by 10 μm or more, and morepreferably by etching the obverse surface of the rolled invar sheet by15 μm or more. Therefore, it can be said that it is effective to etchthe obverse surface of the rolled invar sheet by 10 μm or more, and morepreferably etch the obverse surface of the rolled invar sheet by 15 μmor more in order to restrain the elimination of a metal oxide fromaffecting the form accuracy of a through-hole formed by etching a metalmask substrate.

As described above, it is possible to obtain advantages mentioned belowaccording to one embodiment of a method for manufacturing a metal masksubstrate, of a method for manufacturing a vapor deposition metal mask,of a metal mask substrate, and of a vapor deposition metal mask.

(1) The thickness of the invar sheet 11 is 10 μm or less, and it is thuspossible to set the depth of a mask opening formed in the invar sheet 11at 10 μm or less. Therefore, it is possible to reduce a part that ishidden by the metal mask 51 for vapor deposition when a film-formationobject is viewed from a deposited particle, i.e., it is possible torestrain a shadow effect, and it is thus possible to obtain a shapeconforming with the shape of a mask opening at the film-formationobject, and, consequently, it is possible to realize high definition offilm formation by use of the metal mask 51 for vapor deposition.

Additionally, when a mask opening is formed in the invar sheet 11, it ispossible to make adhesion between the resist layer 22 and the invarsheet 11 higher than before being roughened. Still additionally, it ispossible to restrain form accuracy from being reduced because of, forexample, the peeling off of the resist layer 22 from the invar sheet 11in the formation of the mask opening. In this respect, it is possible torealize high definition of film formation by use of the metal mask 51for vapor deposition.

(2) It is possible to form a resist layer 22 on either resist formationsurface, i.e., on either the resist formation surface formed from theobverse surface 21 a of the rolled invar sheet 21 or the resistformation surface 21 c formed from the reverse surface 21 b of therolled invar sheet 21. Therefore, it is possible to restrain adhesionbetween the resist layer 22 and the metal mask substrate 10 frombecoming difficult to obtain because of mistaking the surface of anobject on which the resist layer 22 is formed, and, consequently, it ispossible to restrain a yield from being reduced when a metal mask 51 forvapor deposition is manufactured.

(3) It is possible to reduce the complexity of handling of the invarsheet 11 that results from the fragility of the invar sheet 11 caused bythe fact that the thickness of the invar sheet 11 is 10 μm or less whenthe invar sheet 11 is conveyed or when post-processing is applied to theinvar sheet 11.

(4) An external force does not act on the invar sheet 11, and thereforethe invar sheet 11 is restrained from being rumpled or distorted incomparison with a case in which the support layer 12 is physicallypeeled off from the invar sheet 11.

The above-described embodiment may be modified as follows.

The support layer 12 may be physically peeled off from the invar sheet11. In other words, an external force may be applied onto at leasteither one of the support layer 12 and the invar sheet 11 so thatpeeling-off occurs in an interface between the support layer 12 and theinvar sheet 11. Even in the thus configured configuration, it ispossible to obtain an advantage equivalent to the aforementionedadvantage (1) by performing a roughening operation so that the surfaceroughness Rz of the resist formation surface becomes 0.2 μm or more andby etching the rolled invar sheet 21 so that the thickness in the rolledinvar sheet 21 that has been etched becomes 10 μm or less.

It is preferable to chemically remove the support layer 12 from themetal mask substrate 10 by use of alkaline solution in order to restrainthe invar sheet 11 from being rumpled or distorted as described above.

When the obverse surface 21 a and the reverse surface 21 b of the rolledinvar sheet 21 are etched, the reverse surface 21 b may be etchedearlier than the obverse surface 21 a, or the obverse surface 21 a andthe reverse surface 21 b may be simultaneously etched. It is possible toobtain an advantage equivalent to the aforementioned advantage (1) byperforming a roughening operation so that the surface roughness Rz ofthe resist formation surface becomes 0.2 μm or more and by etching therolled invar sheet 21 so that the thickness in the rolled invar sheet 21that has been etched becomes 10 μm or less regardless of order in whichthe obverse surface 21 a and the reverse surface 21 b are etched.

An object to be processed in the rolled invar sheet 21 may be only theobverse surface 21 a of the rolled invar sheet 21, or may be only thereverse surface 21 b of the rolled invar sheet 21. Even in the thusconfigured configuration, it is possible to obtain an advantageequivalent to the aforementioned advantage (1) by performing aroughening operation so that the surface roughness Rz of the resistformation surface becomes 0.2 μm or more and by etching the rolled invarsheet 21 so that the thickness in the rolled invar sheet 21 that hasbeen etched becomes 10 μm or less.

If the object to be processed is only the obverse surface 21 a in therolled invar sheet 21, it is preferable to stack the support layer 12 onthe reverse surface 21 b before etching the obverse surface 21 a andthen etch the obverse surface 21 a in a state in which the rolled invarsheet 21 and the support layer 12 are stacked together. If the object tobe processed is only the reverse surface 21 b, it is preferable to formthe support layer 12 on the obverse surface 21 a before etching thereverse surface 21 b and then etch the reverse surface 21 b in a statein which the rolled invar sheet 21 and the support layer 12 are stackedtogether. Likewise, this configuration makes it possible to obtain anadvantage equivalent to the aforementioned advantage (3).

Even if the object to be processed is either the obverse surface 21 a orthe reverse surface 21 b or even if the object to be processed is boththe obverse surface 21 a and the reverse surface 21 b, the object to beprocessed in the rolled invar sheet 21 may be etched in a state in whichthe support layer 12 is not formed at the rolled invar sheet 21. Even inthe thus configured configuration, it is possible to obtain an advantageequivalent to the aforementioned advantage (1) by performing aroughening operation so that the surface roughness Rz of the resistformation surface becomes 0.2 μm or more and by etching the rolled invarsheet 21 so that the thickness in the rolled invar sheet 21 that hasbeen etched becomes 10 μm or less.

In this case, the metal mask substrate may be arranged so as not to havethe support layer 12, i.e., may be arranged so as to include only theinvar sheet 11. Alternatively, the metal mask substrate that is alaminate consisting of the invar sheet 11 and the support layer 12 maybe obtained by obtaining the invar sheet 11 from the rolled invar sheet21 and then stacking the support layer 12 on one surface of the invarsheet 11.

As shown in FIG. 21, if the material forming the support layer 12 ispolyimide, when the support layer 12 is removed from the metal masksubstrate 10, only a part that overlaps with the through-hole 11 c ofthe invar sheet 11 in the thickness direction of the metal masksubstrate 10 among all parts of the support layer 12 may be removed fromthe invar sheet 11. In other words, when the support layer 12 is removedfrom the metal mask substrate 10, only a part that is an edge part ofthe support layer 12 and that is a part other than parts positionedoutside all through-holes 11 c among all parts of the support layer 12may be removed in a plan view facing the reverse surface 11 b of theinvar sheet 11.

In the thus configured configuration, a metal mask 61 for vapordeposition is composed of the invar sheet 11 and a polyimide frame 12 ahaving a rectangular frame shape. The invar sheet 11 has a plurality ofthrough-holes 11 c, and the polyimide frame 12 a has a rectangular frameshape and surrounds all through-holes 11 c in a plan view facing thereverse surface 11 b of the invar sheet 11.

The polyimide frame 12 a of the metal mask 61 for vapor deposition canfunction as an adhesive layer when the metal mask 61 for vapordeposition is attached to the frame 52. Therefore, the metal mask 61 forvapor deposition is attached to the frame 52 in a state in which thepolyimide frame 12 a among all parts of the metal mask 61 for vapordeposition is in contact with the frame 52.

As shown in FIG. 22, if the material forming the support layer 12 ispolyimide, the support layer 12 is not required to be removed from themetal mask substrate 10. In the thus configured configuration, a metalmask 62 for vapor deposition is composed of the invar sheet 11 havingthe through-holes 11 c and the support layer 12 overlapping with theentire reverse surface 11 b of the invar sheet 11 at a point when themetal mask 62 for vapor deposition is bonded to the frame 52.

In the same way as the polyimide frame 12 a, the support layer 12 of themetal mask 62 for vapor deposition can function as an adhesive layerwhen the metal mask 62 for vapor deposition is attached to the frame 52.Therefore, the metal mask 62 for vapor deposition is attached to theframe 52 in a state in which the support layer 12 among all parts of themetal mask 62 for vapor deposition is in contact with the frame 52.

In the thus configured metal mask 62 for vapor deposition, it isrecommended to remove, from the invar sheet 11, only a part thatoverlaps with the through-hole 11 c of the invar sheet 11 in thethickness direction of the metal mask substrate 10 among all parts ofthe support layer 12 after the metal mask 62 for vapor deposition isattached to the frame 52. In other words, it is recommended to removeonly a part that is an edge part of the support layer 12 and that is apart other than parts positioned outside all through-holes 11 c amongall parts of the support layer 12 in a plan view facing the reversesurface 11 b of the invar sheet 11.

FIG. 23 shows a plane structure of an invar sheet, i.e., a planestructure in a plan view facing a resist formation surface that isobtainable by etching an object to be processed in the rolled invarsheet 21. In FIG. 23, dots are given to a first particle trace and to asecond particle trace in order to clarify the distinction between thefirst and second particle traces and the other parts in the resistformation surface.

As shown in FIG. 23, if the thickness by which an object to be processedof the rolled invar sheet 21 is etched is 3 μm or more and 10 μm orless, a surface to be processed 71 a for resist of an invar sheet 71 hasa plurality of first particle traces 72 and a plurality of secondparticle traces 73. Each of the first particle traces 72 is a hollowthat has a hemispherical shape, and the first diameter D1, which is thediameter of the first particle trace 72, is 3 μm or more and 5 μm orless.

Each of the second particle traces 73 is a hollow that is shaped like anelliptic cone, and the second diameter D2, which is the major axis ofthe second particle trace 73, is 3 μm or more and 5 μm or less, andmajor axes in the second particle traces 73 are uniform. The major axisdirection in each of the second particle traces 73 is a directionparallel to the rolled direction of the invar sheet 71.

The invar sheet 71 is normally manufactured by rolling, and thereforethere are not a few cases in which particles composed of oxides, such asa deoxidizer that is added during a process for manufacturing the invarsheet 71, are mixed into the invar sheet 71. Part of the particles thathave been mixed into the obverse surface of the invar sheet 71 areextended in the rolled direction of the invar sheet 71 so as to beshaped like an elliptic cone with the major axis aligned with the rolleddirection. If such particles remain in a part in which a mask opening isformed in the surface to be processed 71 a for resist, there is a fearthat etching to form the mask opening will be hindered by the particles.

In this respect, the aforementioned configuration makes it possible toobtain the following advantage.

(5) The aforementioned particles have already been removed from thesurface to be processed 71 a for resist, and therefore the surface to beprocessed 71 a for resist has the second particle traces 73 shaped likean elliptic cones with aligned major axes, respectively. Therefore, whena mask opening is formed, it is also possible to make the form accuracyor size accuracy of the mask opening higher than in a case in which theparticles remain in the invar sheet 71.

The material forming a rolled metal sheet and the material forming ametal mask sheet and a metal sheet may be materials other than invar ifthe material is a pure metal or an alloy.

Each step of the manufacturing method of the metal mask 51 for vapordeposition may be performed with respect to a rolled invar sheet pieceobtained by being beforehand cut into a size corresponding to one metalmask 51 for vapor deposition. In this case, it is possible to obtain amask for vapor deposition by removing the resist mask and the supportlayer from an invar sheet piece corresponding to the rolled invar sheetpiece.

Alternatively, each step of the manufacturing method of the metal masksubstrate 10 may be applied to the rolled invar sheet 21 that has a sizecorresponding to the metal masks 51 for vapor deposition while the metalmask substrate 10 that has been obtained may be cut into a metal masksubstrate piece that has a size corresponding to one metal mask 51 forvapor deposition. Thereafter, forming a resist layer, forming a resistmask, etching an invar sheet, and removing a support layer may beapplied to the metal mask substrate piece.

The metal mask 51 for vapor deposition may have a shape, such as asquare shape, other than the rectangular shape or may have a shape, suchas a polygonal shape, other than the quadrilateral shape in a plan viewfacing the obverse surface 51 a.

An opening in the obverse surface 51 a and an opening in the reversesurface 51 b among the through-holes 51 c of the metal mask 51 for vapordeposition may each have a shape, such as a square shape or a circularshape, other than the rectangular shape.

If the aforementioned one direction is a first direction, and adirection perpendicular to the first direction is a second direction ina plan view facing the obverse surface 51 a, the through-holes 51 c maybe arranged as follows. In detail, the through-holes 51 c along thefirst direction make one row, and the through-holes 51 c are formed withpredetermined pitches in the first direction. In every other row of thethrough-holes 51 c, the positions in the first direction are equal fromeach other. On the other hand, in mutually adjoining rows in the seconddirection, positions in the first direction in the through-holes 51 cmaking one row deviate by about ½ pitches with respect to positions inthe first direction in the through-holes 51 c making one other row. Inother words, the through-holes 51 c may be arranged in a staggeredmanner.

In short, in the metal mask 51 for vapor deposition, the through-holes51 c are merely required to be arranged correspondingly to thedisposition of an organic layer formed by use of the metal mask 51 forvapor deposition. The through-holes 51 c are arranged correspondingly tothe lattice array in the organic EL device in the embodiment, whereasthe through-holes 51 c in the aforementioned modification are arrangedcorrespondingly to the delta array in the organic EL device.

If the aforementioned one direction is a first direction, and if adirection perpendicular to the first direction is a second direction ina plan view facing obverse surface 51 a, each of the through-holes 51 cis away from the other through-holes 51 c adjoining in the firstdirection and from the other through-holes 51 c adjoining in the seconddirection in the aforementioned embodiment. Without being limited tothis, the opening in the obverse surface 51 a of each of thethrough-holes 51 c may be continuous with the opening in the obversesurface 51 a of each of the other through-holes 51 c mutually adjoiningin the first direction, or may be continuous with the opening in theobverse surface 51 a of each of the through-holes 51 c mutuallyadjoining in the second direction. Alternatively, the opening in theobverse surface 51 a of each of the through-holes 51 c may be continuouswith the opening in the obverse surface 51 a of each of thethrough-holes 51 c mutually adjoining in both the first direction andthe second direction. In the thus configured vapor deposition metalmask, the thickness of a part at which two through-holes 51 c arecontinuous with each other may be smaller than the thickness of a partthat is at the outer edge of the vapor deposition metal mask and atwhich the through-hole 51 c is not positioned, i.e., than the thicknessof a part at which etching has not been performed in a step of formingthe through-hole 51 c.

Without being limited to a vapor deposition metal mask that is used informing the organic layer of the organic EL device, the vapor depositionmetal mask may be a vapor deposition metal mask that is used whenwirings of various devices, such as a display device, other than theorganic EL device are formed or when functional layers or the like ofvarious devices are formed.

DESCRIPTION OF THE REFERENCE NUMERALS

10 . . . Metal mask substrate; 11, 31, 71 . . . Invar sheet; 11 a, 21 a,31 a, 41 a, 51 a . . . Obverse surface; 11 b, 21 b, 31 b, 41 b, 51 b . .. Reverse surface; 11 c, 23 a, 31 e, 41 c, 51 c . . . Through-hole; 12 .. . Support layer; 12 a . . . Polyimide frame; 21 . . . Rolled invarsheet; 21 c, 71 a . . . resist formation surface; 22 . . . Resist layer;23 . . . Resist mask; 31 c . . . First hole; 31 d . . . Second hole; 41. . . Metal mask sheet for vapor deposition; 51, 61, 62 . . . Vapordeposition metal mask; 52 . . . Frame; 53 . . . Adhesive layer; 72 . . .First particle trace; 73 . . . Second particle trace; C . . . Centralpart; S1 . . . First surface layer part; S2 . . . Second surface layerpart.

The invention claimed is:
 1. A method for manufacturing a metal masksubstrate, the method comprising: preparing a rolled metal sheet havinga length extending from one end to an opposing end of the rolled metalsheet and the rolled metal sheet including an obverse surface and areverse surface that is a surface located opposite to the obversesurface, at least one of the obverse surface or the reverse surfacebeing an object to be processed; reducing a thickness of the rolledmetal sheet, along the length of the rolled metal sheet, to 10 μm orless by etching the object to be processed by 3 μm or more by use of anacidic etching liquid such that a maximum thickness of the rolled metalsheet is 10 μm or less, and roughening the object to be processed sothat the processed object becomes a resist formation surface that has asurface roughness Rz of 0.2 μm or more, wherein a metal mask sheet isconfigured for through holes to be formed in areas of the metal masksheet having a thickness of 10 μm or less.
 2. The method formanufacturing a metal mask substrate according to claim 1, wherein theobject to be processed comprises both the obverse surface and thereverse surface.
 3. The method for manufacturing a metal mask substrateaccording to claim 1, wherein the object to be processed is either theobverse surface or the reverse surface, the method further comprisingstacking a plastic support layer on a surface located opposite to theobject to be processed, the object to be processed is etched in a statein which the rolled metal sheet and the support layer are stackedtogether, thereby obtaining a metal mask substrate, in which the metalmask sheet and the support layer are stacked together.
 4. The method formanufacturing a metal mask substrate according to claim 2, wherein theetching includes etching a first object to be processed that is eitherthe obverse surface or the reverse surface and then etching a secondobject to be processed that is the remaining one of the obverse surfaceor the reverse surface, the method further comprises etching the firstobject to be processed and then stacking a plastic support layer on theresist formation surface that has been obtained by etching the firstobject to be processed, the second object to be processed is etched in astate in which the rolled metal sheet and the support layer are stackedtogether, thereby obtaining a metal mask substrate in which the metalmask sheet and the support layer are stacked together.
 5. The method formanufacturing a metal mask substrate according to claim 1, wherein therolled metal sheet is a rolled invar sheet, and the metal mask sheet isan invar sheet.
 6. The method for manufacturing a metal mask substrateaccording to claim 1, additionally comprising forming through holes inthe metal mask sheet.
 7. The method for manufacturing a metal masksubstrate according to claim 1, wherein after the roughening of theobject to be processed the method further comprises: forming a resistlayer on the processed object; forming a resist mask by subjecting theresist layer to patterning; etching completely through the metal masksheet from the resist mask side of the metal mask sheet to form thethrough holes between the obverse surface and the reverse surface,wherein through hole connection portions are eliminated.
 8. A method formanufacturing a vapor deposition metal mask, the method comprising:forming a metal mask substrate that includes at least one resistformation surface; forming a resist layer on the one resist formationsurface; forming a resist mask by subjecting the resist layer topatterning; and etching the metal mask substrate by use of the resistmask, wherein the metal mask substrate is formed by use of the methodfor manufacturing a metal mask substrate according to claim
 1. 9. Themethod for manufacturing a vapor deposition metal mask according toclaim 8, wherein the metal mask substrate includes a laminate of themetal mask sheet and a plastic support layer, and the method furthercomprises chemically removing the support layer from the metal masksubstrate by exposing, to alkaline solution, the metal mask substrate,on which the resist mask has been formed.